Of course, Winfrey was thrilled to answer this question. "OK, so here's the authenticity moment," she begins. "Laughing at myself as a young TV anchor woman, I had this moment where I realized I can be a better me than I can be a pretend Barbara Walters -- and that's what changed my life. From that moment forward, I felt more like talking like myself and being like myself."

Dropping even more wisdom, Winfrey continues, "Your ability to show the truth of you is also somebody else's truth and that when people can see that, that is what they're relating to."

Witherspoon also shares what has kept her going in this business. "Whenever I accomplished something, instead of feeling good about it, I was always pushing myself to think, 'Well, what now? What's next?' I'm just really obsessed with learning and pushing myself to be knowledgeable about things I don't know."

Annie Leibovitz/Vanity Fair

As for Kidman, she says she got into acting because it serves as an "outlet" for all her emotions. "That's what pulls me through," she explains. "That's my authentic self."

When Hanks is asked about authenticity, he ponders the age-old question, "What is your big break?"

"In truth, the big break is the very first time anybody asks you to do it professionally," he shares. "That's the break that begins everything else. But really, the only reason you're doing it is for the sheer joyful experience."